
cube([15,25,3]);
translate([7.5,-10,0]) 
  scale([1,5,1])
  cylinder(r=4, h=3, $fn=50);
for ( i = [1.5 : 3 : 15] ){
  for ( j = [2 : 3 : 23] ){
    translate([i,j,0])
     cylinder(r=0.5+(j-2)/60,h=25,
        $fn=14 - (i-1.5)/3*2);
  }
}